Hydraulic press fluid supply with pressure intensifier



Feb. 26, 1952 L M 2,587,571

HYDRAULIC PRESS FLUID SUPPLY WITH PRESSURE INTENSIFIER Filed Sept. 13,1946 INVENTOR DANIEL L. LOMBARD ATTORNEY Patented Feb. 26, 1952HYDRAULIC PRESS FLUID SUPPLY WITH PRESSURE INTENSIFIER Daniel L.Lombard, Hubbard, Ohio, assignor to Lombard Corporation, Youngstown,Ohio, a

corporation .of Ohio Application September 13, 1946, Serial No. 696,906

- 6 Claims. 1 This invention relates to hydraulic actuation of metalextruding presses and the like and more particularly to improvedapparatus for supplying hydraulic fluid pressure to presses generallyand to improved control systems for such apparatus. In certain pressoperations, as in the metal extrusion field, for example, it isessential that extremely high hydraulic fluid pressures ,be developedfor proper operation of the press and as extremely high pressures cannot be readily developed in a practical manner by the use of pumps ithas heretofore been proposed to employ pressure intensifiers of thedifferential piston area typein conjunction with the press. These priorsystems, however, are very complicated and expensive and limit the speedof operation of the press to such an extent that their use is largelyavoided whenever possible.

It is the primary object of the present invention to provide a hydraulicfluid supply and asso-' ciated control system for a hydraulic presswhich is economical to construct, flexible in operation, capable ofprecise control, and which does not mitigate against the cyclic speed ofoperation of the press.

A more specific object of the invention is the provision of a hydraulicfluid pressure intensifying system and an associated control system fora hydraulic press in which the various operative control valves arelocated in the relatively low pressure side of the system while yetcapable of effecting complete and simplified control over the, operationof the press.

Anotherobject of the invention is the provision of an improved systemfor supplying intensified hydraulic fluid pressure to a metal workingpress and the like in which provision is made for limiting theapplication of the intensified pressure only to the extent required in aparticular cycle of operation at hand and in which provision is made forenabling the pressure intensifying installation to be adequatelyserviced and maintained without materially decreasing the output orcapacity of the installation. The above and other objects and advantagesof the invention will become apparent upon consideration of thefollowing detailed specification and theaccompanying drawing whereinthere is disclosed a preferred embodiment of the invention.

The single figure of the drawing is a schematic representation of ahydraulic press actuator and control system therefor constructed inaccordance with the principles of the invention.

Referring to the drawing in detail, referencenumeral Ill indicates themain cylinder of a the cylinder Ill and suitable means as a conduit 16may be employed to conduct fluid pressure into the ends of cylinders l5adjacent the cross head I3 to retract the ram H in the cylinder II). Aconduit l I conducts fluid pressure into the closed end of cylinder I0to advance the ram l I through its working stroke.

A source of hydraulic fluid pressure comprising a conduit 18 is providedand, in actual practice, this source may comprise the outlet of a pumpbut more preferably the outlet of a series of ganged pumps connected inparallel. Associated with the source i8 is a three-way valve I9 havingports also connected with conduits 20 and 2|, respectively. Any suitablecontrol may be provided for the valve 19 as, for example, the lever 22and, as shown, when this lever is in neutral or N position the conduitsI8, 20, 2| are all blocked but when the lever is moved to position Aconduit IB is connected with conduit 2| and when the control lever ismoved to position B conduit i8 is connected with conduit 20.-I-Iydraulic fluid supplied the conduits l8 and 2i is utilized toactuate the main cylinder I 0 of the;

press and through apparatus now to be described this source of fluid isalso utilized to develop a much higher or intensified pressure to raisematerially the load capacity of the press. It should: be observed,however, as the description proceedsthat the increased pressure is notapplied to any of the controlled valves, particularly during the timesthat any of such control valves are actuated.

Conduit 2| is interconnected with conduit ll by means of a conduit 23.

The hydraulic pressure intensifier utilized in the system of theinvention comprises a pair of' rigidly connected to a piston 28 which isslideably.

received in cylinder 24. A conduit 29 having a manual'valve 30interposed therein connects the supply conduit 2| with the lower end ofcylinder 24 and the upper end of the pressure chamber or cylinder 25 isconnected with the conduit 23 by means of a manual valve 3i. 'As shown,the u p-.v

. 3 interconnected with port 2..

per end of cylinder 24 above the piston 28 is provided with a port whichis connected to a conduit 32. For purposes to be hereinafter more fullydescribed two or more of the pressure intensiflers thus described arepreferably utilized in each installation and such intensifiers areconnected in parallel, the valves 30 and 3| being employed to select thenumber of units in use at any particular time as will be understood. Aninterconnecting conduit 33 is employed to connect the upper ends of thecylinders 24 in parallel and with the conduit 32.

Positioned in the conduit 23 between the valve 3| and the conduit 2| isa normally open solenoid valve 34, the energizing coil 35 of which is ina series circuit including a suitable current source and a normally opensolenoid switch 49. The switch 49 is actuated by a solenoid 48 which maybe held energized by normally closed limit switches 36 positioned in thebottom of cylinder 25 or initially energized by a pressure responsiveswitch 31 which is actuated by the pressure in conduit 2|, saidactuation occurring upon the pressure in conduit 2| reaching apredetermined value. It should therefore be understood that the valve 34will be open when the pistons 28 are in their lowermost position,provided that the pressure in conduit 2I has not exceeded theaforementioned predetermined value at which the pressure responsiveswitch 31 is actuated.

I provide a four-way control valve 38 having ports I, 2, 3 and 4, asshown, and it will be observed that ports 2 and 4 are connected to anexhaust conduit 39 while port I is connected with conduit 29 by means ofconduit 40 while port 3 is connected with conduit 32 leading from theupper ends of cylinders 24. Valve 38 is provided with two fluid pressureoperated actuators 4i and 42, respectively, and an opposing spring 43.The construction of valve 38 (which is a conventional type of relayvalve readily procurable in the market) is such that so long as fluidpressure is supplied to neither of the actuators M and 42 port I isconnectedonly with port 3 and viceversa while upon the application ofpredetermined fluid pressure to actuator 4i port I is blocked and portUpon the application of fluid pressure to actuator 42 port I isconnected with exhaust port 4. and port 3 is connected to port 2.. Tocontrol valve 38 in the manner to be hereinafter morev fully describedactuator 4| is interconnected with conduit .49v by means of a conduit 43while actuator. 42 is connected by means of a conduit. 44. to one of theports of a three-way pilot valve 45. The second port of valve 45 isconnected to the. source conduit I8 by means of conduit 46 while thethird port is connected to exhaust by means of a conduit 41. Valve 45may be coupled with the valve I9 so that when control lever 22 is inposition A conduit 44 is connected to exhaust conduit 4'! when controllever is moved into position B to retract the main ram I I the conduit44 is connected with the supply conduit 46. The mechanicalinterconnection between the valves I9 and 45 may be made adjustable sothat ports I and 4 of valve 38 are interconnected just ahead of thesupplying of fluid pressure to conduit 20 when lever 22 is moved toretracting or B position.

Considering now the operation of the above described system as a whole,the pistons 28 will normally be at their lowermost positions at thestart of a cycle of operation and the ram I I will be fully retractedand the space in cylinder III as well as the spaces in the pressureheads 25 and in the cylinders 24 above pistons 28 will be fully filledwith liquid. Operators 4! and 42 of valve 38 are at this timedeenergized so that only ports I and 3 of valve 38 are interconnected.Valve 34 is open. To initiate a cycle of operation the control lever 22is moved to position A and fluid pressure is admitted to conduit 2Ithrough valve I9 and thence into the cylinder ID by means of conduits 23and I1. Ram II moves rapidly forward through the idle portion of itsWorking stroke and, of course, the same pressure which is at this timeapplied against the ram II appears in the lower ends of cylinders 24 bymeans of conduit 29 but since conduits 29 and 32 (leading to the upperends of cylinders 24) are interconnected by way of conduit 49 and portsI and 3 of valve 38 and since the fluid in the pressure chambers 25 isin open communication with the conduit 23 through open valves 3I thepistons 28 will be in equilibrium and will have no upward motion, thusinsuring that the intensifiers are held inactive until their higheroutput pressure is required at the ram.

Upon the punch or ram I2 engaging the work and the press meeting itsfull resistance to further operations, the fluid pressure will build upin conduit 2| and upon a predetermined pressure valve being obtained,the pressure responsive switch 31 will close thereby energizing solenoid48 and closing the switch 49, thus completing the circuit throughsolenoid 35, thereby energizing said solenoid to quickly and positivelyclose valve 34. This higher pressure acting on valve actuator 4I throughconduits 29, 40 and '43 shifts valve 33 to connect ports 3 and 2',providing an exhaust outlet for the liquid contained in the annularspaces in cylinders 24 above the pistons 28. With the pump pressure thenacting only upon the lower surfaces of pistonsv 28, rams 21 rise incylinders 25, forcing the liquid contained therein out through conduits23 and IT and into the press cylinder it. It should be observed thatthis arrangement of maintaining a back pressure on.

the pistons 28 during the time that hydraulic fluid is flowing directlyinto the main press cylinder II] from the source I8 to the valve 34insures the continuance of the retraction of the intensifier rams untilsuch time as increased pressure is actually required by the main presscylinder I0.

There is thus. made available for-high pressure actuation of the. presscylinder the full fluid capacity of the intensifiers.

. The-liquid displaced by'the rams 21 will of course be a function oftheir area and length of stroke. Actual practice therefore willdetermine the size and number of intensifiers to be used in anyparticular system. It is .usually advantageous, however, to use severalsmall units: connected in parallel, the principal advantage being thatif in any particular installation the work at hand requires but slighthigh resistance move ment of the press ram Ii, all but one or twointensifiers may be isolated from the system by means of valves 30 and 3I. Another advantage of the use of a multiplicity of intensifiers isthat some of them may be out of service at all times for maintenance orother purposes without affecting the continuity of operation of theplant.

Outward movement of the main ram I I ofthe press is ultimately arrestedeither by a stop on the press or by the cessation of fiuid flow due tothe rams 27 having reached their uppermost positions. If it is desirednow to retract the press the control lever 22 is'moved' to position Btherebylconnecting supply conduit [8 with the head ends of pull-backcylinders l5 through conduits 20 and I6 and to relieve the pressure inthe cylinder I to allow the ram to retract the actuator '42 is energizedby means of valve 45 in the manner described above to interconnect portI to port 4 and port 3 to port 2 of valves 38 thus relieving pressure inconduit 2-8 and providing a fluid intake passage into the annular spacesimmediately above the pistons 28 of the intensifiers. Immediately uponpressure decrease in conduits 40 and 29 valve actuator 4| and pressureresponsive switch 3'! are de-energized. The system remains unafiected,however, since valve 38 is being actuated by the actuator 42 and thevalve 34 is being held closed by the limit switches 36 which are in theholding circuit shown for the relay 48, 49. It should be understood thata portion of the fluid which .issues from the cylinder l0 uponretraction of theram ll goes into the chambers 25 to keep these chambersfilled and to force the rams 2'! downwardly. The excess fluid isexhausted throughconduits 29, 48 and 39.

Upon the pistons 28. of the intensifiers reaching their lowermostpositions switches 36 are opened. These switches are preferablyconnected in parallel so that both of them must be opened to deenergizethe relay coil 48, thereby de-energizing solenoid 35, allowing valve 34to open in re-cycling the system preparatory to the next succeedingcycle of operation. It should be observed that this arrangement insuresthat the intensifier rams will be fully retracted at the end of eachcycle of operation so that durin the next succeeding cycle of operationthe intensifiers may deliver their maximum volumetric capacity of highpressure fluid, as explained above.

The relief valve 50 is provided for the purpose of providing an outletfor the hydraulic fluid contained in the pull-back cylinders l duringforward movement of the press. During the initial or high speed movementof the press the fluid discharged from cylinders [5 through the valve 58is added to the conduits 48, 29, 23 and I7 due to the interconnection ofports I and 3, as explained above, so that there is, in efiect, areduction in the effective area of the main press cylinder therebyincreasing the speed of initial movement of the press. However, upon thepress meeting its higher resistance to movement and the consequentinterconnecting of port 3 of valve 38 (conduit 32) with the exhaust port4 of valve 38 the remaining fluid in the cylinders I5 is discharged toexhaust, thereby allowing the main press cylinder to exert its maximumdriving force.

It should now be apparent that I have provided improved apparatus forhydraulic press actuation and an improved control system for suchapparatus. Through the adoption of the principles of the invention it ispossible, while using a minimum number of simply constructed parts, toactuate and control a hydraulic press at greater cyclic speeds and withmaximum force which is automatically applied when required and which maybe made effective only to the extent required in the particular work athand. Further, and of more importance, is the fact that the systemprovides extremely high pressures for actuating the press but none ofthe control valves are in any of the high pressure lines. Rather, allthese valves are in the low pressure lines and this contributesmaterially to the economy and durability of the system. The apparatus isfurther simplified in that the operation of the press is always underthe precise and instantaneous control provided by the valves [9 and 45which, in turn, are actuated by the lever22.

The above specifically described embodiment of the invention should beconsidered as illustra tive only as obviously many changes may be madetherein without departing from the spirit or scope of the invention.Reference should therefore be had to the appended claims in determiningthe scope of the invention.

What I claim is: t

1. In hydraulic fluid supplying apparatus for a press cylinder thecombination of a primary source of hydraulic fluid under pressure, acontrol valve and conduit means interconnecting said source and saidpress cylinder, a pressure intensifier comprising a first cylinderhaving a piston therein and a second cylinder communieating with saidpress cylinder and having a ram therein coupled with said piston, meansto simultaneously connect both ends of said first cylinder with saidsource, means to close said valve. upon the fluid in said conduit meansattaining a predetermined pressure, and means to thereafter relieve thefluid pressure on the ram side of said piston.

2'. Apparatus according to claim 1 further characterized in that saidmeans to relieve comprises means responsive to the attainment of apredetermined maximum pressure in said conduit means.

3. Hydraulic fluid supplying apparatus for a press cylinder comprisingin combination a source of hydraulic fluid under pressure, a conduitinterconnecting said source and said cylinder, a pressure intensifierhaving a high pressure cylinder interconnected with said press cylinderand an operating cylinder associated therewith, a ram in said highpressure cylinder, a piston in said operating cylinder rigidly connectedwith said ram, conduit means interconnecting said source with both endsof said operating cylinder, means responsive to the attainment of apredetermined back pressure in said source to block said conduitinterconnecting said source and said press cylinder, and meansresponsive to the attainment of a predetermined back pressure in saidsource to relieve the fluid pressure in the ram end of said operatingcylinder.

4. Hydraulic apparatus comprising a press cylinder, a source ofhydraulic fluid under pressure, a conduit interconnecting said sourceand said cylinder, a normally open solenoid-operated valve in saidconduit, a fluid pressure intensifier having its high pressure cylinderconnected with said press cylinder and its low pressure cylinderconnected to said source, a ram in said high pressure cylinder coupledwith a piston in said low pressure cylinder, a switch responsive to thepressure in.said source to establish an energizing circuit for saidsolenoid operated valve whereby said valve is closed upon apredetermined back pressure being reached in said source, and a switcharranged to be. operated upon said ram reaching its fully retractedposition to de-energize said solenoid operated valve, the arrangementbeing such that during retraction movement of the press and saidintensifier said ram must reach a fully retracted position before saidvalve is opened.

5. In hydraulic apparatus having a press cylinder, a source of fluidpressure, and a pressure intensifier having a high pressure cylinderwith a ram therein and a low pressure cylinder having a pistonthe'reinconnected with said ram; the combination of a first conduitinterconnecting said high pressure cylinder and said press cylinder, 8,second conduit interconnecting said source and the outer end of said lowpressure cylinder, a third conduit including a normally open valve.interconnectin said source and said first conduit, a fourth conduit anda three-Way valve to normally maintain fluid from said source in theinner end of said low pressure cylinder, said threeway valve having anexhaust port, the arrangement being suchthat at the start. of a cycle ofoperation. fluid from said source is furnished directly to said presscylinder through said third conduit while said ram is held in retractedposition by the back pressure in said high pressure cylinder and by theback pressure in the inner end of said low pressure cylinder, meansresponsive to the attainment of a predetermined back pressure in saidsource to close said valve in said third conduit, and means responsiveto the attainment of a predetermined back pressure in said source toshift said three-way valve whereby the fluid in the inner end of saidlow pressure cylinder is exhausted to allow forward movement of saidram.

6. Apparatus according to claim 5 further including a single-actingpress pull-back cylinder, valve means and a fifth conduit to connectsaid source to said pull-back cylinder, a pressure relief valve.interconnecting said pull-back cylinder and said fourth conduit wherebyduring the initial low pressure actuation of said press cylinder thefluid contained in. said pull-back cylinder is added to the fluid of thesource to increase the speed of movement of said press cylinder Whileafter actuation ofv said three-way valve the remaining fluid containedin said pull-back cylinder is exhausted to thereby allow saidv presscylinder to exert its maximum force.

.DANIEL L. LOMIBARD'.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 206,501 Taylor July 30, 18781,927,085 Dinzl Sept..19, 1933 1,966,421 Towler July 10, 193.4 1,970,999Ferris Aug. 21, 1934 2,030,966 Crane Feb. 18, 1936 2,058,377 FrancisOct. 20, 1936 2,142,628 Ballert Jan- 3, 1939 2,408,513 Gunderson Oct. 1,1946 2,452,292 Cousino Oct. 26, 1948 2,481,991 Ernst Sept. 13, 1949FOREIGN PATENTS Number Country Date 43 Great Britain Jan. 2, 1893 4,170Great Britain Feb. 25, 1893

